Commonly-owned U.S. Pat. No. 4,642,833 to Stoltz, et al. (the “Stoltz Patent”) discloses various valve assemblies useful for automatic swimming pool cleaners. These assemblies typically include flexible, tubular diaphragms surrounded by chambers, with the diaphragms interposed in the fluid-flow paths (i.e. “in-line”) through the cleaners. In response to variation in pressure internally and externally, the diaphragms contract and expand transversely along at least part of their lengths, thereby controlling fluid flow therethrough.
Commonly-owned U.S. Pat. No. 4,742,593 to Kallenbach (the “Kallenbach Patent”) discloses additional valve assemblies for use with automatic swimming pool cleaners. These assemblies, also typically tubular and of flexible material, too may be interposed in-line, within the fluid-flow paths of such cleaners. According to the Kallenbach Patent:                The body [of the tubular valve] has an intermediate section between the ends that assumes a substantially collapsed condition over a segment thereof in absence of a pressure differential between the interior and exterior. The section preferably is collapsed transversely over a segment.See Kallenbach Patent, col. 1, ll. 28-32.        
International Publication No. WO 02/01022 of Kallenbach, et al. (the “Kallenbach Publication”), entitled “Swimming Pool Cleaner,” details another cleaner in which a valve periodically interrupts a flow of water through the body of the cleaner. Included in the cleaner are a main flow path and a by-pass passage built into the body. See Kallenbach Publication, p. 5, ll. 8-11. Also included in one version is an “annular resilient rolling diaphragm” with an edge “located in sealing engagement with the inner wall of the body.” Id., p. 6, ll. 24-26. However, a dome-shaped valve closure member, rather than the rolling diaphragm, operates to interrupt fluid flow through the main path. Additionally, neither the rolling diaphragm nor the dome-shaped member is interposed in-line in the main water path from the inlet passage of the cleaner to the outlet of the body.
U.S. Pat. No. 4,351,077 to Hofmann (the “Hofmann Patent”) describes yet another cleaning apparatus in which a valve interrupts fluid flow through the cleaner body. This valve, denoted a “flapper,” oscillates so as periodically to open and close the flow passage through the body. See Hofmann Patent, col. 2., l. 67 through col. 3, l. 2. Opposite the flow passage within the body is a so-called “suction communication,” which is closed when the flow passage is open and opens briefly when the flow passage is closed. See id., col. 3, ll. 9-22.
Each of the Stoltz, Kallenbach, and Hofmann Patents and the Kallenbach Publication discusses “suction-side” cleaners in which a pair of concentric pipes exist, the outer of the pipes being adapted for connection to a flexible hose leading (directly or indirectly) to the inlet, or “suction side,” of a pump. An annular gap between the pipes permits water to flow through the by-pass passage of the cleaner of the Kallenbach Publication toward the flexible hose. A similar gap in versions of cleaners discussed in the Stoltz and Kallenbach Patents offers “suction communication . . . through slots [in a plate] to [a] chamber” defined at least in part by the tubular members of these patents. The contents of the Kallenbach Publication, together with those of the Stoltz, Kallenbach, and Hofmann Patents, are incorporated herein in their entireties by this reference.